Building Bridges



Building Bridges

Introduction:

This simulation will show the students the effects of an external force on different types of bridge structures. Students will learn about different types of bridge structures and supports for these structures before beginning the simulation.

This simulation addresses grade 7, cluster 3: Forces and Structures. It is called Engineering for Earthquakes, and is found at the URL: . Here, students, working in pairs, will use the handout and follow concise directions before building their bridge. As a teacher, you will have to ensure that students are following instructions, as opposed to just playing with the simulation, to guarantee maximum learning.

Why use this simulation??

In accordance with the ‘Five Attributes of Meaningful Learning’, the Engineering for Earthquakes simulation involves active manipulation of different bridge structures (Jonassen et al., 1999, p.170). The website teaches students about the different parts of the bridge and reinforcements they can use. It gives them the opportunity to build a bridge, and allows them to observe its strength by testing it against an earthquake of a certain magnitude. This simulation is very realistic in that it gives specific fault lines, and shows specific locations on a map. The website intentionally teaches how forces act on different structures, and gives students all the information required to make informed decisions. Students will work cooperatively, sharing ideas and discussing the outcomes of their choices.

Strengths:

• Requires active manipulation

• Website is very informative

• It is extremely visual

• Allows students to make mistakes, yet entices them to try different structures based on their acquired knowledge

• It simulates real life

Weaknesses:

• Without guidance, students may just go through the motions without putting thought to their actions

• There is an element of trial and error without consequence, therefore, students will not understand the research, time and effort required to build a bridge

Curriculum Objectives:

7-3-07 Investigate to determine that the effect of a force on a structure depends on its magnitude, direction, and point and plane of application.

7-3-09 Describe and demonstrate methods to increase the strength of materials

7-3-11 Evaluate a structure to determine the appropriateness of its design, using the design process.

7-3-12 Use the design process to construct a structure that will withstand the application of an external force.

Teachers Notes:

• Give students handout in class before going to the computer lab.

• Read the entire document with them before starting. This will give the students an idea of what is expected of them in the lesson.

• Stop the class after step 11 to discuss the implications of the experiment they just did.

- Why did it not work?

- What bridge structure do you think would be stronger?

• Topics of discussion (possibly for the next day):

- Was anybody able to build a bridge to withstand the maximum earthquake?

- Tell us about your bridges.

- Which bridge type was the best suited to the location and magnitude?

- Did anyone build a bridge that withstood an 8.2 magnitude earthquake on the San Andreas fault line, but not an 8.0 magnitude earthquake on the Hayward fault line? Why do you think this happened?

- Think about actually constructing the bridge without a simulation. How long would it take? How would you find out which structures are best? How much money would it cost?

Conclusion:

- Earthquakes are external forces that act on bridges, affecting their structural strength and stability.

- Through this simulation, we have learned about different types of bridge structures and the additional features that can be used to support these structures.

- It is clear that different magnitudes of earthquakes affect structures in varied ways. It is also important to note that the distance from the epicenter to the structure will affect its impact.

- There are many variables involved in building a structure like a bridge, including location, soil type, proximity to fault lines, bridge types and their supports to name a few. When building a bridge, engineers need to factor in all of this information and research the possibilities that would work best before beginning the design process.

References:

Build Your Bridge. Engineering For Earthquakes. Retrieved September 19, 2007 from

Jonassen, D.H.; Peck, K.L.; & Wilson, B.G. (1999). Learning With Technology: A Constructivist Perspective. Columbus: Merrill.

Name: ____________

Date: _____________

Building Bridges

This simulation will show the effects of an external force on different types of bridge structures. You will learn about several types of bridge structures and supports for these structures before beginning the simulation.

Objectives:

In this lesson, you will learn that the effect of a force on a structure depends on its magnitude and direction. You will describe and demonstrate methods to increase the strength of materials. Using the design process, you will construct a structure that will withstand the application of an external force.

HERE IS YOUR TASK…..

1) Before starting the simulation, please review the following definitions. They will help you complete your task. The web simulation will provide you with further information regarding each bridge type used.

Bridge Types

[pic]

Beam Girder: These bridges are composed of steel and concrete. They are relatively cheap to build and are sturdy enough for many purposes.

Steel Arch: This sturdy bridge is composed of steel and reinforced concrete, and can span broad rivers and mountain valleys.

Cantilever – Truss: This bridge requires strong and lightweight materials like iron and steel for its rigid structure. The truss is the part of the bridge that involves the triangular formations on the top and/or bottom of the bridge.

Suspension: Traditionally, this bridge was built with vines and handmade ropes. Today, the bridge is built with steel, and strong cables run between the tower and the anchorage. Secondary cables run from the main cables to support the deck.

Cable – Stay: This bridge is similar to the suspension bridge except that the main cable supports the deck directly.

2) In partners, go to the URL:



3) Once you get to the bridge simulation, click onto ‘Add Safety Features’

4) Name the four different types of safety features and explain why you would use these features to support your bridge.

1- _________________

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2- _________________

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3- _________________

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4- _________________

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5) Select ‘Build Your Bridge’.

6) Click and drag the Steal Arch bridge to all three segments.

7) Select ‘Add Safety Features’.

8) Add all possible safety features to each segment.

9) Select ‘Test Your Bridge’.

10) Select the San Andreas fault line at an 8.2 magnitude. TEST IT!

11) Click on ‘Test Your Bridge’, select the Hayward fault line at an 8.0 magnitude. TEST IT!

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12) Before beginning your own simulation, write down what bridge type and supports you would use to build your bridge. Keep in mind any combination of bridge types and supports can be used. Be sure to include reasons for your selections.

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13) Select ‘Build Your Bridge’. Click on desired bridge type and drag it to one of the segments.

14) Add safety features through the ‘Add Safety Features’ section.

15) Your bridge will need to withstand an 8.2 magnitude earthquake on the San Andreas fault line, AND an 8.0 magnitude earthquake on the Hayward fault line. Click on ‘Test Your Bridge’, select a fault line and magnitude. TEST IT!

16) Draw a picture of the bridge you described in step 5. Please use rulers and clearly label each bridge type and support used.

17) Did your bridge withstand the force of the earthquake? Why or Why not?

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18) At what magnitude did your bridge become damaged or collapse?

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19) What change(s) do you think will make your bridge stronger?

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20) Keep testing new bridges until you find one that can withstand one or both of the earthquakes.

21) What bridge worked best?

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22) Explain why this is the optimal bridge type for these locations.

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